In attempting to find a solution to illegal immigration, it’s worth studying the root cause of the great majority of illegal entry into the United States. Individuals from poorer countries, mainly Mexico, want to work in the United States. Per-capita GDP in the US is roughly four times that in Mexico, so it’s easy to see why labor is trying to flow towards employment.

If illegal immigrants come to the US to find work, then the easiest way to stop illegal immigration is to remove that incentive. Federal and state governments can easily step up enforcement against businesses which hire undocumented workers, and can increase the fines to the point that it is uneconomical to hire illegal workers. Once the cost of hiring an undocumented worker exceeds that of hiring a documented worker, businesses will naturally follow the profit motive.

The Obama administration has accelerated business audits, quadrupling the previous administration’s efforts in that area. If employer audits were expanded and targeted at those sectors known to use illegal labor most heavily, demand for illegal labor would drop immediately. That in turn would decrease the number of would-be employees crossing into the US, as job opportunities thin out.

Effective enforcement of employment law, even against small businesses, would significantly reduce new illegal immigration. Once the flow of illegal immigrants is slowed from the current 500,000 per year to a trickle, an answer for how to deal with the 12 million among us today can be sought. But until businesses find that hiring illegal workers is unprofitable, the immutable laws of capitalism will cause laborers to find their way to the jobs.